Shaft mounting



Aug. 12, 1958 J. P. WATSON 2,346,835

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United States Patent SHAFT MOUNTING James P. Watson, Lynwood', Calif.

Original application March 22,1954, Serial No. 417,598, now Patent No.2,732,719, dated January 31, 1956. Divided and this application March21-, 1955,, Serial No. 495,496

Claims. (Cl. 745) This invention relates, to improved features ingyroscope and particularly to an improved method and means for caging agyroscope.

This is a division of my co-pending patent application Serial No.417,598, filed March 22, 1954, for Gyroscope, now Patent No. 2,732,719,issued January 31, 1956.

Air, land and sea vehicles and other apparatus of all types makeextensive use of gyroscopes for control purposes; The gyroscope forms astable space reference against which the attitude of its vehicle may be.compared to all times. Under certain circumstances it is desirable tobring the inner gimbal and" the outer, gimbal of the gyroscope into apredetermined attitude or relation with respect to the housing or frameof the gyroscope. Such an operation is known as caging, and when theinner girnbal and outer gimbal have been fixed, in such a predeterminedattitude with respect to the frame the gyroscope is said to be caged.

It is an object of this invention to provide an improved method andmeans for caging a gyroscope.

It is another object of this invention to provide a rap idly operatingmethod and means for caging a gyroscope. It is a further object of thisinvention to provide a method and means for caging a gyroscope whichrequires only a small amount of energy for the cagingoperation,

and which subjects the gimbals and girnbal bearings: of the gyroscope toonly a low stress.

In many gyroscope uses the outer gimbal isfree to to:

tate through 360, although the inner girnbal is generally restrained bystop members to an operating range of;

perhaps 170. The inner girnbal. is generally thus restrained because, ifthe rotor shaftis allowed to become.

coaxial with the outer gimbal axis, there is danger. of the outergirnbal spinning freely inresponse to the reaction:

torque from the rotor or gyroscopic wheel. However, though manygyroscopes t-hus permit a wide range of angular operations of both theouter and inner gimbals,

many caging systems of the past, have been solimited.

Having caged the gyroscope, the time arrives when it, must be uncaged,that is, the gimbals must be freed to turn freely with respect tothe-frame and each otherin response to any change in attitude of theframe;

and false torques and precession may besuffered'by' one or both gimbals,thus starting the gyroscope-off inthe' wrong attitude.

It is therefore an object of this invention to providea caging means fora gyroscope which may be uncaged quickly.

Furthermore, in the uncaging operation it-is essential If the. uncagingis done slowly there" is danger that undesiredz" "ice that there be nounwanted kick or torque applied to the gyroscope during the uncagingprocedure.

It is, accordingly, another object of this invention to provide a methodand means for uncaging a gyroscope which is free from any danger ofapplying undesired torques to the gyroscope parts during the uncagingoperation.

It is a further object of this invention to provide a method and meansfor caging a gyroscope in which the gimbals are brought into cagedposition through the shortest travel path, thereby minimizing cagingtime.

It is a further object of this invention to provide in a gyroscopecaging mechanism improved means for sensing a sensing means as abovewhich also serves as a latching means for latching the gimbals in cagedposition.

Many air vehicles, particularly missiles, are subjected to very highacceleration forces. These accelerations thusprovide a powerfuloperating force which is capable of operating or actuating mechanismwithin the missile unless the mechanism is specifically designed toguard against such undesired or false operation.

It is an object of this invention to provide a gyroscope caginganduncaging means which is virtually free from danger of such false orfaulty operation through high vehicle acceleration.

One of' the most serious mishaps which might occur with the gyroscopemechanism of an air vehicle is to have the gyroscope accidentally cagedduring flight of the:

revert-to uncaged position of the gyroscope in the event.

of:power'failure in the caging circuit.

Itis'a further object of this invention to provide acaging and uncagingmechanism the bulk of which is mounted on .the frame instead of on thegimbals, thereby minimizing the danger of unwanted movement of thegimbals under high, acceleration forces, such as impact forces.

The mounting of the stationary portion of the spin motor or. gyroscopewheel to the inner girnbal must be extremely precise and free frommovement.

It is'an object of this invention to provide an improved mounting for agyroscope wheel shaft to the inner girnbal of the: gyroscope.

It' is'another object of this invention to provide improved means forfirmly and accurately mounting an elongate member, such as a shaft,between and within the arms of: a bifurcated support member; towithstand shocks, without'displacement between shaft and support.

his another object of this invention to provideimproved means for firmlyand precisely mounting any relatively rigid member between two fixed,extended arms movement with an absolute minimum of friction in order. tobe. compatible with the small low power requirements.

of precision apparatus of this type.

It is, accordingly, an object' of this invention to provide means formounting a reciprocable actuating oroperating member which is virtuallyfree from friction in its.

operation;

In the assembly of a typical controlling gyroscope many wires areemployed leading to and from the gyroscope. Generally, each wire is madeto fulfill as many functions as it can in order to minimize the weightand space taken by the wiring. v I

It is an object of this invention to reduce to a further minimum thenumber of wires required to effectuate caging and uncaging of agyroscope.

It is another object of this invention to provide a wiring system for agyroscope caging circuit which requires only one wire, in addition tothe two wires which are essential to carry the caging power, for thepurpose of providing adequate control and indication of caging anduncaging.

In housing or in casing apparatus of the general type here underconsideration, it is usually a relatively simple problem to seal theapparatus within the case when the case is cylindrical in form.Gyroscopes like some other types of equipment, however, generally lendthemselves better to housings or cases having flat sides. Such caseshave a tendency to bulge out along their straight or flat edges andwhere this tendency to bulge is most pronounced there results aconsequent sealing problem.

It is an object of this invention to provide an improved seal for acontainer of rectangular form which is uniquely adapted to resist thistendency to bulge on the fiat sides.

In accordance with these and with other objects which will becomeapparent thereinafter, certain preferred forms or embodiments of thepresent invention will now be described.

The method and means of the present invention involves essentiallysuccessive caging of the inner gimbal followed by caging of the outergimbal. While it is recognized that in a certain sense the inner gimbalcannot be regarded as actually caged until it is anchored in apredetermined relation with respect to the frame, it has been foundexpedient herein to regard the inner gimbal as being caged when it isbrought to a predetermined position with respect to the outer gimbalwith which it is pivotally mounted, and to regard the outer gimbal asbeing caged when it is brought to a predetermined position with respectto the frame in which it is mounted. Thus the gyroscope itself is notcaged until both the inner gimbal and the outer gimbal have beensuccessively caged.

In the present invention the caging operation involves essentially asensing of the position of the inner gimbal with respect to the outergimbal. Following this sensing the inner gimbal is rotated in thecorrect direction to bring it to caged position within the outer gimbal.This caged position is generally one in which the spin motor axis issubstantially perpendicular to the outer gimbal axis, although thisparticular relative attitude is not necessarily essential to thepractice of the present invention. This initial sensing of the positionof the inner gimbal within the outer gimbal is important in order toprevent the inner gimbal from being driven in the wrong direction whichwould bring it up against one of its two limit stops thereby subjectingits parts to unwanted strains and stresses and further thwarting one ofthe important objects of this invention which is to bring the gimbals totheir relative caged positions in the shortest time possible.

Following caging of the inner gimbal with the outer gimbal, the innergimbal is latched or secured to the outer gimbal in caged position.

Next the position of the outer gimbal within the frame is sensed. Exceptin cases where the outer gimbal does not have 360 of freedom, thissensing is not essential to the operation of the apparatus, inasmuch asthe outer gimbal is free to turn completely through many revolutions;however, it is highly desirable in order that the controlling mechanismmay know in which direction to drive the outer gimbal in order to bringit to caged position with respect to the frame in a minimum time. Whenthe outer gimbal ha been properly positioned and latched to the frame,caging is complete.

In the present invention, the uncaging is performed in a minimum time byso designing the mechanism that all of the parts which effect theuncaging move in a short straight line as will become more fullyapparent hereinafter. At the same time in one form of the presentinvention the dangerous forces of high acceleration which might causeunwanted operation of the parts are circumvented by using a drivemechanism which is rotary in its operation and therefore not subject tothe high linear acceleration mentioned hereinbefore.

A detailed description of certain forms of the present inventionfollows.

Referring to the drawings, Figs. 1 through 14 inclusive illustrate afirst embodiment of the present invention and Figs. 15 and 16 indicatecertain modifications which may be made thereto if desired.

Fig. l is a perspective view with certain parts partially bro-ken awaymore clearly to illustrate the interior of the gyroscope.

Fig. 2 is a fragmentary section taken on line 2-2 in Figure 1.

Fig. 3 is a cross sectional plan view looking down on the top of thegyroscope with the outer housing or case cut through.

Fig. 4 is a sectional elevation taken on the broken section line 44 inFig. 3.

Fig. 5 is a fragmentary section taken on line 5-5 in Figure 3.

Fig. 6 is a fragmentary sectional view taken on line 66 in Fig. 4.

Fig. 7 is a partial sectional view taken on the angled section line 77of Fig. 3.

'Fig. 8 is a fragmentary sectional view taken generally on the samelines as Fig. 4, but showing certain parts broken away and in greaterdetail.

Fig. 9 is a fragmentary crosssection taken on a line 99 in Fig. 8.

Fig. 10 is a fragmentary view generally similar to Fig. 6 and taken online ll010 in Fig. 8.

Fig. 11 is a fragmentary section of the gyroscopic spin motor taken online 11l 1 in Fig. 4.

Fig. 12 is a fragmentary view taken generally in the come plane as Fig.8 but with certain parts broken away for added clarity.

Fig. 13 is a fragmentary section taken on line 13-43 in Fig. 12.

Fig. 14 is a schematic diagram illustrating the operating circuit of thegyroscope.

Fig. 15 is aview generally similar to Fig. 7 but showing ing a modifiedform of the present invention.

Fig. 16 is a modified form of Wiring diagram employed with the gyroscopein Fig. 15.

Referring to the drawings, 21 designates a generally cylindricalskeleton-like frame including a top plate 22 and a bottom plate 23. Theframe is held together by four bolts 20 (Fig. 1) which clamp the plates22 and 23 together using the cylindrical frame member 21 as a spacer.The gyroscope is mounted to any suitable support 24 by providing adownwardly extending axial member 26 formed on the bottom plate 23 andpassing through a mounting opening in the support 24. A nut 27 serves toclamp the gyroscope to the support 24. By thus mounting the gyroscope atonly one position internal stresses in the gyroscope casing and frameare avoided no matter how tight the nut 27 may be screwed up. Themounting member 26 also constitutes a convenient means for passingelectrical connecting wires (not shown into the gyroscope). For thispurpose pin connectors 2 5' are mounted seesaw ed within t e innergimbal 31 for rotation about an axis perpendicular to the'inner gimbalaxis is a gyroscop-ic wheel or rotor 32.

Afiixed to the lower end of the outer gimbal 29 is an annular member 33and immediately circumjacent thereto is another annular member 34afiixed to the end plate 23 of the frame 21. Together the members 33 and34 constitute a pick-off means, the details of which are not shown andwhich are well known in the art. Such a pick-off means may be magnetic,electrostatic or may constitute an actual physical contact as bypotentiometer. The pickoif means'serves to generate a unique signalwhich may be taken out through the pin connectors 28 to indicate thepositions of the outer gimbal 29 with respect to the frame 21. Insimilar manner a suitable pick-off mechanis m, shown schematically at36, is employed to detect and pick-oif the position of the inner gimbal31 with respect to the outer gimbal 29.

i The upper mounting shaft 37 of the outer gimbal 29 supports aplurality of slip rings 38 which are contacted by brushes 39; by meansof which power and signals may be transmitted to and from the innerportions of thegyroscope A second set of rings and brushes (not shown)completes these circuits from the outer to'the inner gimbal to supplypick-01f and the drive motor of the gyroscopic wheel 32. Such means arewell known in the art and will not be described further in thisspecification.

In accordance with the present invention, means are provided for sensingthe position of the inner gimbal 31 with respect to the outer gimbal 29.Such sensing means includes a disc 41 secured to the inner gimbal 31.Over approximately 90 of its arc the disc 41 is provided with a segment42 having a given radius, andover an adjacent 90 segment 43 the disc hasa slightly larger ra dius. The segment 44 opposite the segment 42- isthe same radius as the segment 42 and the segment 46 opposite thesegment 43 is the same radius as the segment 43. These latter twosegments44 and 46' do not constitute operating portions of the disc 41but are so proportioned simply to provide balance for the assembly. Atthe juncture between the segments 42 and 43 is a notch 47 having atapered bottom portion 48.

Reciprocably mounted in the outer gimbal 29 in position to register withthe disc 41 is a latching and sensing member, probe 49. At its lower endthe probe 49'is provided with a roller 51 engageable with the peripheryof the disc 41. The member 49 reciprocates in a cup-like mounting shell52 secured through and within the gimbal 29, as shown in Fig. 8. Acompression spring 53 acting between the shell 52 and a shoulder 54 onthe probe 49 urges the probe 49 to its upper position away from the disc41. A key-way56 in the probe 49 mates with a small projection 57 formedon the shell 52 to prevent rotation of the probe 49 in the gimbal 29while still permitting reciprocation thereof.

The probe 49 is moved up and down in its sensing operation by means of aring-like actuatingmember S S includinga central hub portion 59 and anannular plate 61 journalled to the central portion 59. The plate 61 iscircular and has a peripheral groove 62 therein in which rides a wheel63 extending from the upper end of the probe or member 49 into thegroove 62. Plate 61 is prevented from turning by a key 65projecting'downward from plate 22, which however does not impedeitsaxial movement. In the uncaged condition there is no contact betweenwheel 63 and plate 61.

The top plate or member 22 of the frame 21 has a central portion 64depending. therefrom and around this portion 64 is mounted the ring-likehub portion 59 which is rotatable therearound and also axially movablethereon. The central hub 59 is rotated by means provided with a pulleygroove 66 in which rides a belt 67, the belt also encircling'a drivepulley 68 secured to a shaft 69 journalled in the plate 22 and extendingtherethrough. The upper end of the shaft 69 extends into a gear box 71,

power for which is derived from a small electric drive motor 72:. Whenthe motor 72 is energized the central hub portion 59 of the actuatingmember 58 will be ro.-. tated. Rotation of the actuating member 58serves to apply a torque to the outer gimbal 29 whenever the hub 59'islatched to the gimbal 29, as will now be described.

Latching of the hub 59 to the gimbal 29 is efiected through driving ring73 locatedwithin an internal cavity 74 formed in the hub 59. andconcentric with the hub 59. The driving ring 73 is provided withinternal threads '16 and is keyed to the hub 59 by the provision of akey-way 77 formed in the hub 59 which mates with a key 78 formed onjthering 73.

Secured to the ring 73 and extending downwardly through an opening inthe bottom plate 79 of the hub 59.

is a torque pin 81 ;'to the lower end of the torque pin 81 is rotatablymounted a small roller 82. The mounting of the roller 82 to the torquepin 81 is resilient and slightly movable so that the roller may move upand down slightly with respect to the pin 81 but is biased to.

its downward position. The roller 82 comes into rolling engagement witha torque ring or rail 83 having a notch therein at a certainpredetermined point in which the roller 82 may engage to latch theactuating member 58 to the outer gimbal 29. When thus latched to thegimbal- 29, theactuating member 58 serves to apply a torque to thegimbal 29.

The actuating member 58 is moved downwardly with respect to the frame 21by the provision of a pivoted thread engaging member 84 having at itslower end a toe 86 which may be selectively moved outward intoengagement with the thread 76 in the driving ring, 73.

If desired a plurality of members 84 may be provided spacedcircumferentially about ring 73 in order to prevent cramping. Suchmembers 84 may be actuated by a common solenoid 107.

When the hub 59 is rotating and the toe 86 is engaged in the thread 76,the rotation of the ring 73 effected through the keying 7778 causes thering'73 to screw downwardly within the hub cavity 74.

This downward screwing of; the driving ring 73 is transmitted to thecentral'hub 59 through an annular compression spring 87 locatedcoaxially in the cavity 74.

In thus screwing down, the ring 73 also operates against the upward biasof a spring 88, the lower end of which rests on an annular ledge 89secured to the central frame member 64.

Thus as the actuating member 58 is moveddown by the action of thedriving ring 73, the probe member 49, and more particularly the roller51 thereof, is brought into engagement with the periphery of the innergimbal disc 41. The annular plate 61 is preferably journalled for freerotation with respect to the central hub 59 by means of a series ofballbearings 91. This is done in order to minimize friction between thenon-rotating plate Bearing 91 61 and; the rotating hub 59 during caging.and key may be omitted if desired, uniting parts 61 and 59. The onlyeffect of this simplification would be to introduce a slight torque onthe outer gimbal through roller 63.

As the driving ring 73 screws down pressing the actu already incagedposition so that the roller 51 enters directly into the notch 47.Thiswould simply accelerate thev whole procedure as will presently beseenhereinafter. Engagement of 'the roller 51 with the disc 41 brings toa haltthe downward motion of the actuating member 58, thus the initialaxial position of the central hub 59 is determined by the angularposition of the inner gimbal 31 intheouter gimbal 29.

The-driving ring 73 continues to screw down until the roller 82-engagesthe torque rail orring83. At this momentthe thread engaging toe 8 6.snaps into an annular,

groove 92 formed at the upper end of the thread 76 and of somewhatlarger radius. In this position the ring 73 may be rotated in eitherdirection and still remain held down by the toe 86, for rotation of thehub member 59 then continues in one direction or the other until theroller 82 snaps into the V-notch 85. Thus the outer gimbal 29 ispositively latched to the central hub 59 and further torque appliedthrough the belt 67 results in the application of a torque in onedirection or the other to the outer gimbal 29.

As has been pointed out hereinbefore, in the initial downward movementof the actuating member 58, it is first stopped in a position dependentupon the angular attitude of the inner gimbal 31. This attitude issensed by a mechanism including certain peripheral concentric camsurfaces formed on the outside of the central hub 59. The lower of thesecam surfaces is disposed immediately above the pulley groove 66 and isdenominated 59a. Immediately above the cam surface 59a is an annular camsurface 59b of larger radius than 59a. Above the surface 59b is a camsurface 59c.

The axial region corresponding to the surface 590 is divided angularlyinto two portions, the first portion being denominated 590 as shown inFig. 7 and being of radius equal to that of 59a. This arcuate segment isapproximately 180", the remaining 180 of this axial region beingoccupied by a cam section 5900 which is of radius equal to that ofsection 59b.

The above mentioned cam surfaces actuate a probe 93 which in turnactuates a reversing microswitch 94 mounted to the upper frame plate 22.The switch actuating probe 93 is secured to the upper frame plate 22 forlimited longitudinal reciprocation by a U-shaped leaf spring member 95,the details of which are essentially similar to those describedhereinafter in connection with Fig. to which reference is made forfurther understanding. The switch 94 is single pole double throw. Whenthe actuating member 58 is in upper position as shown in Fig. 7 theactuating probe 93 is in engagement with the surface 59a and the switch94 is in its upper position in Fig. 14. If in the initial downwardmovement of the actuating member 58 the roller 51 comes into engagementwith the higher cam segment 43, the cam surface 59a is still inengagement with the switch operating probe 93. If, however, the roller51 is in registry with the segment 42 so that it does not engage thedisc 41 until it has moved down far enough to touch the segment 42 thenthe cam surface 5% has been brought into engagement with probe 93 andthe switch 94 has been actuated to its lower position in Fig. l4.

The mechanism thus described constitutes a means for sensing andtranslating angular position of the disc 41 into a desired linearposition of the reversing switch 94 to control precession of the innergimbal 31 either clockwise or counter-clockwise in order thereby tobring the roller 51 into engagement in the notch 47. The circuit foreffecting this selective precession of the inner gimbal and theoperations thereof will be described hereinafter. The inner gimbal isprecesse-d in the desired direction by applying a torque in the properangular direction to the outer gimbal 29. This torque is applied throughthe torque pin 81, actuating member 59 and belt 67 by the motor 72.

The inner gimbal is thus rotated by precession in the proper directionuntil the roller 51 drops into the groove 47. When the roller 51 is thusin registry with the notch 47 it does not drop all the way down to thebottom but drops to an intermediate position shown at 51c in Fig. 10. Itis prevented from dropping all the way down by the engagementof a smallwheel 96, extending outwardly from the top of the probe 49, with a track97 formed by an inturned flange on a depending cylindrical track support98 mounted to the upper frame plate 22. The track 97 is concentric withthe outer gimbal 29 as shown in Fig. 7 and extends all the waytherearound.

Fundamentally the wheel 96 is mounted on an arbor 99 which isessentially fixed with respect to the probe 49 but which in practice isactually mounted for a slight vertical adjustment because ofmanufacturing tolerances as will be explained more fully hereinafter. Inthus coming to rest on the rail 97 the wheel 96 causes the arbor 99 tobe pressed against an overhanging ledge 101 formed above the slot 102 inthe mounting probe 49 in which the arbor 99 is jourualled by a pivot pin103. (Fig. 12.) When the roller 96 is thus engaged to roll on the railor track 97, the roller 51 on the bottom of probe 49 is in the position51c in Fig. 10. This esse tially locks the inner gimbal with respect tothe outer gimbal in caged position of the inner gimbal. There is aslight tolerance in this locking or latching action, however,represented by the difierence in width between the notch 47 and thediameter of the roller 51. This loose fit is provided in order topreclude any jamming of the parts.

With the probe 49 in this position the actuating member 59 is in such aposition that the reversing switch probe 93 is in engagement with eitherthe cam segment 590 or 5900. Thus the reversing switch 94 is inwhichever position will cause the outer gimbal 29 to be rotated to cagedposition through the minimum distance and hence in the minimum time.

The caging of the outer gimbal with respect to the gyroscope frame 21 iselfected through the provision of a V-notch 104 (Fig. 13) formed at apredetermined position in the frame track 97. When the outer gimbal 29has been rotated in the proper direction by the actuating member 58until the wheel or roller 96 is in registry with the V-notch 104, thewheel 96 snaps down into the notch 104 thus allowing the entire assemblyto which it is mounted to drop down a slight distance. This now permitsthe roller 51 to drop fully into engagement with the lower V-surface 48of the notch 47 thus firmly latching the inner gimbal to the outergimbal without play or creep. At the same time the outer gimbal islatched in similar manner to the frame 21 by the engagement of the wheelor roller 96 in the V-notch 104.

It is quite important that both gimbals be latched in their cagedposition without play or backlash and to this end the latchingnotchesare both made in V shape. However, since the same member namely theprobe 49 carries both of the caging rollers 51 and 96, the roller 96 ismounted with the slight up and down freedom described hereinbefore inconnection with Fig. 12. To this end a small leaf spring 1% is mountedto the upper end of the probe member 49 and bears downwardly on thearbor 99 to keep the wheel 96 pressed into engagement with the V-notch194. The spring 196 is quite firm but is not strong enough to overcomethe general downward pressure exerted on the assembly generally by thespring 87 backed by the driving ring or nut 73.

The caging operation is instituted by energization of a solenoid 107mounted atop the upper plate 22 and ha ing a plunger 108 extendingtherefrom. A compression spring 109 biases the plunger 198 to inwardposition. The uter end of the plunger 108 is pivoted at 111 to thepivoted thread engaging member 84 which is in turn pivoted to the upperframe plate 22 at 112. Thus when the lunger 1% is moved outward thethread engaging toe 86 is moved into engagement in the thread 76.

The plunger 103 carries a laterally extending arm 113 which engages atransfer microswitch 114 (Fig. 3). The switch 114 is a single poledouble throw switch (Fig. 14) and is so positioned as to be actuatedfrom one posi tion to the other when toe 86 snaps into the uppercircular groo e 92 in the driving ring 73. The transfer switch 114serves to transfer control of the motor 72 to the re versing switch 94as seen by reference to Fig. 14.

As the annular plate 61 of the actuating member starts to move down anuncaged microswitch 116 (Fig. 5) is caused to be actuated. The switch116 is a simple .9 single pole, single throw switch which is inclosedposition when the annular plate 61 is in uppermost position and isin open position at all other times. This open position is produced by asmall spring located inside the switch .which operates as soon aspressure is removed fro-m the actuating member 117.

Switch 116 is actuated by up and down movement of plate 61 through avertical, reciprocably mounted actuating pin 118, the upper end of whichengages the member 117, the lower end being engaged by plate 61. The pin118 is relieved at each end and the relieved portion fits 'into a holeformed in the respective ends of a pair of leaf spring members 119 and121. As shown in Fig. the pin 118 passes throughthe upper frame plate 22by means of a bore 122 which is sufficiently larger than the pin 118 Itoprovide complete clearance. Each of the leaf spring members 119 and 121is appreciablywider than it is thick and each is appreciably longer thanit is wide. One end of the leaf springtmember 121 is mounted to theplate 22 of the frame 21 and the other leaf spring member 119 is mountedat one endto the cylindricalframe member 21. The. respective freeendsofthe members 119, and 121 are substantially aligned vertically andreceived the respective ends of the pin 118 as mentioned hereinbefore.Thecomfbination is biased away from switch 116 sufficiently to resistanticipated acceleration forces that would tend to utilize the mass ofactuator 118 to operate switch 116. This also relieves switch 116 of theadded work of dis- ,placing actuator 118 before it can reset itself tothe open position. This arrangement insures that switch 116 will openwithout fail as soon as plate 61 starts to move down. The pin 118 isthus mounted for limited back and forth l(ii1 this case up and down)movement without any rubbing friction of any kind and with thepossibility of sticking completely eliminated. Although the path ofmovement of each end of the pin 118 is slightly arcuate, the anglecovered by the arc is so slight by virtue of the fact that the switch116 is a micro-switch requiring very small travel for actuation, that itis in effect a linear movement which is virtually friction free. Inunstressed position .of the leaf spring members 119 and 121 their freeends arespaced apart a distance slightly less than the oppositeshoulders formed where the pin 118 is relieved 'at each end. Thus thepin 118 is held firmly in engagement between the members 119 and 121.

The purpose of the uncaged switch 116 is to indicate to the externalsensing and controlling circuit that the gyroscope is fully uncaged.

The uncaged switch 116 has its counterpart in a caged switch 123 (Fig.8) mounted atop the upper frame plate 22, and actuatedby a .reciprocableactuating pin 124. The pin 124 is mounted'for limited longitudinalreciprocation between a pair of leaf springs 126 and 127, in a mannersimilar to that described hereinbefore in connection with the pin 118,except that the spring 127 urges pin 124 strongly toward switch 123 soas to maintain the switch in the operated position (the upper positionin Fig. 14) except when spring 127 is forced and held down by roller 96.The leaf spring 127 extends beyond its link with the pin 124 and servesalso as an actuating member effective to be engaged by the roller orwheel 96 when the wheel 96 drops into the V-notch 104 in the track 97,as shown inFig. 13.

The caged switch 123 is a single pole, double throw switch which ismaintained in its lower position in Fig. 14 whenever the leaf springmember 127 is engaged by the roller 96, and which is in its upperposition in Fig. 14 at all other times. I

The principal function of the caged switch 123 is to indicate to theexternal circuit that the gyroscope is fully caged.

. The circuit involved in the present invention is shown in Fig. 14wherein the dotted line 134 represents schematically the confines of thegyroscope itself. Leading to the gyroscope are a pair of powerconductors 136 to 10 which is applied a conventional power supply, asfor example, volts D. C. In one of the conductors is an external switch137 selectively operable to effectuate the caging operation ofthegryoscope. When the switch is open the gyroscope is uncaged, and ifalready caged will revert to uncaged position, as will be describedhereinafter.

It will be noted that the solenoid 107 is connected directly across thefull 110 volts but that a voltage dropping resistor 138 is interposed inthe circuit to the motor 72 which is generally a 28 volt D. C. motor.The resistor 13S drops the voltage down to approximately 56 volts. Thisvoltage is further split in twoby a pair of series connected impedancemeans in the forms of resistors 139 and 141. The motor 72 is connectedbetween the juncture point between these resistors 139 and 141 and theswitch arm of the double throw reversing switch 94 when the transferswitch 114 is in the lower position. Thus when the switch 94 is in upperposition the current will flow from right to left in the motor 72 withthe circuit being completed through the resistor 141, and when theswitch 94 is in the lower position current will flow from left to right,with the circuit being completed through the resistor 139. In this waythe direction of motor rotation may be changed by means of a simplesingle pole, double throw switch at 94. v

All of the switches in Fig. 14 are shown in the attitude which theyassume when the gyroscope is uncaged, that is 'when the circuit is deenergized, as by opening of the external switch 137. As. the gycroscopecompletes its caging operation, the last step is for the switch 123 tomove from its upper to its lower position, thereby deenergizing themotor 72 and leaving only the solenoid 1G7 energized to keep the drivingring or nut 73 depressed through continued engagement by thethread-engaging lever 84. The uncaged switch 116 is open at all timesexcept when the gyroscope is completely uncaged. Its function is toindicate through the indicating conductor .142 that the gyroscope isfully uncaged.

Such indication is made through a pair of lights 143, which is a greenlight, and 144, which is a red light. Voltage dropping resistors 146 areconnected in series with the lights 143 and 144 simply to dissipate theexcess voltage, since the lights 143 and 144 are generally designed forless than the full circuit voltage.

In the uncaged position, shown in Fig. 14, current flows through thegreen lamp 143, thence across the bridging conductor 142 and switch 116to the other side of the line through the resistor 138. The resistanceof 138 is so low compared to the resistances 144 and 146 that forpractical purposes it may be regarded as a shunt circuit around the redlamp 144 so that the red lamp does not glow at all. In the cagedposition of the gyroscope the switch 123 is in its lower position andthe switch 116 is open. Under this circumstance it is the green lamp 143which is shunted while the red lamp 144 receives the full line voltage,compensated for of course by its series resistance 146; thus the redlamp glows fully and the green light is out when the gyroscope is fullycaged.

v During the caging or uncaging operation, that is when the parts areoperating in the manner which will be described hereinafter, the switch123 is in its upper position while the switch 116 is open, thus the linevoltage is applied in series across the two lamps 14 3 and 144, and eachlamp will glow dully to indicate that the parts are in operation andthat the gyroscope is neither caged nor uncaged fully.

,It is to be understood that in addition to the D. C. control and cagingcircuit, illustrated in Fig. 14, other circuits are brought into thegyroscope for furnishing power for the gyroscopic wheel and also forpick-off purposes, as described hereinbefore. The gyroscopic wheel powermay be alternating current and such power is also employed for heatingthe gyroscope through a plurality of elongateheaters 147 which arestrapped to the clamping bolts 20 (Fig. 1). The current through theheaters 147 1 1 is controlled by the thermostatic element 148 (Fig. 3)which is spaced away from the heaters 147 and separated therefrom by theupper frame plate 22.

It is important that the gyroscope be well sealed against entry ofdeleterious elements and to that end a special sealing means isprovided, as hereinafter described. Setting over the entire gyroscope isan open-ended case 151. The bottom plate 23 of the gyroscope frameconstitutes a closing plate closing the end of the case 151, as best isseen in Figs. 2 and 4. The lower plate 23 is provided with a relievedportion 152 which fits within the open bottom end of the case 151.Circumjacent the periphery of the relieved portion 152 is a groove 153having a resilient sealing O-ring 154 seated therein which is slightlycompressed between the bottom of the groove 153 and the inside surfaceof the case 151 to form a continuous seal around the bottom plate 23,between plate 23 and the case 151.

In order to keep the case 151 clamped firmly to the bottom plate 23, theouter face of the plate 23 is provided with a groove 156 which isadjacent and paralleling each of the four edges of the plate 23. As bestseen in Fig. 2, the groove 156 is slanted outwardly toward the edge 157of the plate 23. Because of the fact that the corners of the plate 23and the case 151 are rounded, as shown at 158 (Fig. 1), each of the fourgrooves 156 opens onto the rounded portion of the corners, as shown inFig. 1.

Each of the four sides of the case 151 is provided with a similar groove159 which is adjacent and parallel to the bottom edge 157. The grooves159 likewise are slanted outwardly toward the edge 157 as shown in Fig.2, residing in the grooves 156 and 159 on the respective four sides ofthe case are four C-shaped channel members 161 having re-entrant flanges162 engaged in the grooves 156 and 159 to clamp the case 151 firmly downagainst the bottom plate 23. The channel members 161 are slipped intothe respective grooves 156 and 159 from the corners of the case sinceeach of the grooves 156 and 159 communicate with the edge of the plateand case, respectively, as best seen in Fig. 1.

The channel members 161 are provided with partial transverse slots 163which give a certain flexibility to the channel members so that eachchannel member functions as a plurality of individual segments insecuring its particular portion of the case 151 to the bottom plate 23.

The overall effect of this manner of mounting is to provide a very firmclamping of the case 151 to the bottom plate 23, particularly at thoseportions of the casing edge located between any two adjacent corners. Itis at this region where the ballooning effect of the rectangular case ismost acutely felt, that is to say, there is rarely any clamping problemat the corners where the geometry of the parts insures rigidity, butthere is a tendency intermediate the corners for the edges of the casingto pull away from the closing plate. By the present clamping method,such tendency is overcome by the relatively firm channel members 161which exert downward forces to secure case 151 to plate 23 and an inwardforce to maintain contact between case 151 and seal ring 154. Theseclamps have the added advantages that they can be installed and removedwithout special tools and once in place will not loosen or changeposition under the most severe conditions.

While the channel members 161 have been described as being slipped infrom the respective edges of the grooves 156 and 159, it is possiblealso to construct them with sufiicient resilience so that they may besnapped into the grooves directly from the sides instead of being slidin from the ends.

In any event it is preferred to make the members 161 sufficientlyresilient that they will recover from any distortion due to temperaturecycling of the secured parts.

It is important in the mounting of the gyroscopic wheel or rotor thatthere be no shifting whatever between the rotor shaft and the innergimbal to which it is mounted.

12 In accordance with the present invention means are provided forinsuring such a firm mounting.

Referring to Fig. 11, the rotor 32 is shown mounted rotatably to a shaft171 by means of ball bearings 172. in the present instance the rotor ison the outside of the stator 173 which is affixed to the shaft 171. Thisprovides the spinning mass with its greatest moment of inertia byplacing the mass as far from the rotative axis as possible. This ofcourse is desirable in any gyroscope equipment.

The shaft 171 is fitted Within the inner gimbal 31 and is secured firmlythereto in accordance with the present invention by a securing pin 174.As seen in Fig. 11, the shaft 171 is butted against the inner gimbal 31at 176. The shaft 171 and the gimbal frame 31 have aligned bores 177 and178 respectively, of equal diameter. The bore 177 in the shaft 171 iscontinued by a threaded bore 179 having a slightly smaller diameter thanthe bore 177 and forming a coaxial inner continuation thereof. The innerend of the pin 174 is reduced slightly in diameter and is threaded toengage the bore 179 in the shaft. The unthreaded smooth portion of thepin 174 is fitted closely within the aligned bores 177 and 178.

The outer surface of the gimbal frame 31 is recessed to receive the head181 of the pin 174 which thus bears against the gimbal 31 to hold theshaft 171 in close abutting engagement with the inside surface of thegimbal 31.

The construction illustrated in Fig. 11 results in the shear forcesbeing resisted by the closely fitting pin 174 at the butting plane 176while separation forces between the gimbal 31 and the shaft 171 areresisted by the threaded engagement of the inner end of the pin 174 inthe threaded bore portion 179 and the head 181 bearing against thegimbal 31. The net result is a precise firm fitting which is capable ofresisting normal wear and tear and high shock forces without measurableshift between the rotor and the gimbal.

The shaft 171 is hollow as shown at 182 and communicates with the stator173 through an outward passage Through this passage wires 185 are ledinto the stator through the pin 174 which is also hollow as shown at184. To accommodate the wires 185 during assembly of the gyroscope wheelto the gimabl 31 a lateral groove 186 is formed inside the gimbal 31.These wires reside in the groove 186 during the last phase of theassembly just as the shaft 171 is moved into butting relation within thegimbal 31.

Although only one end of the rotor shaft 171 has been shown in Fig. 11,it will be understood that the same construction is employed at theother end of the shaft where it engages the opposite arm of the innergimbal frame 31.

It will be readily seen that this mounting feature is applicable to thefirm and precise mounting of any member between and within two spacedarms or trunnions, for example the arms of a bifurcated support member.

At the other end, the lateral groove 186 may be omitted from the gimbal31 if desired, although it is preferable from the standpoint of massproduction to provide both sides of the gimbal frame 31 with grooves136, in order to simplify fabrication and assembly. Furthermore, it maybe desirable at times to bring control wires in and out of the rotor atboth ends of the shaft 171.

An alternative means of moving the actuating member 58 downward is shownin Fig. 15. In this embodiment the driving ring or nut 73 is eliminatedand is replaced by one or more solenoids 191 mounted in the upper frameplate 22'. The plungers 192 of the respective solenoids 191 bear againstthe annular plate 61 and press the actuating member 58' down directlyinto engagement with the gimbal. In the embodiment shown in Fig. 15 thetorque pin 81' is secured directly to the central hub portion 59 of theactuating member. Also eliminated are the solenoid 107; switch 114; arm84 and spring 87 of the first the solenoid 107a nd the transfer switch114is eliminated.

Operation The operation of the apparatus described hereinbefore will nowbe described with particular reference to Figures 7; '8, and 14.

When the switch 137 stands open the gyroscope is uncaged and the greenlight 143 is lit, which will indicate this condition. Caging isinstituted by closing the'switch 137 and leaving it closed. Closing'ofthe switch 137 applies voltage simultaneously to the solenoid 107 andthe motor '72' through the transfer switch 114. Energizingof'the motor72 causes'the central hub portion 59 to be rotated: in 'a givendirection by the belt 67. At the s'ametime the solenoid 107 causes thethread engaging toe 8 6 to engage the bottom portion of the thread 76,(Fig. 8 iri'the driving ring 73.

"Rotation of the hub 59 is imparted to the ring 73 through the key 78and causes the ring 73 to be screwed downward. As the ring 73 movesdownward within the cavity74, it presses the actuating hub 59 ahead ofit through the intermediacy of the spring 87.

Initial downward movement of the annular plate 61 causes operation ofthe uncaged switch 116 through the pin 118 (Fig. The switch 116 is leftopen, placing both of the lights 143 and 144 in series across the powersupply. This causes the green light to cease to glow brightly andinstead both the green and red lights will glow dully to indicate thatthe parts are operating and that the gyroscope is neither fully cagednor fully uni caged.

The ring 73 continues to move downwardly until the toe snaps into theouter annular groove 92. Simultaneoiisly, the resiliently mounted roller82 is brought into engagement with the torque ring or track 83 on theouter gimbal 29. As the toe 86 snaps into the groove 92 the r esultingmovement of the lever 84 and solenoid plunger 108 causes actuation ofthe transfer switch 114 which transfers control of the motor 72 to thereversing switch 94. a

' The position of the reversing switch 94 will depend upon what hashappened in the meantime to the sensing probe 49 as it was moved down bythe annularplate 61. If the roller 51 has gone into engagement with thehigh segment 43 on the disc 41 (see 5111, Fig. 10) then the downwardmovement of the actuating member 58 will have been halted at such aposition that the switch opcrating probe 93 is still engaged with thecam surface 59a.

In this event the motor 72 continues to rotate in the same directionsince the reversing switch 94 has not been operated. Continued rotationof the motor 72 in the forward direction causes the roller 82 to movearound on the torque ring 83 until it snaps into the notch 85 therein,whereupon the outer gimbal 29 is firmly latched or coupled to theactuating member 58 and torque is applied to gimbal 29 through thetorque pin 81. This torque applied to the gimbal 29 is in the properdirection to cause the inner gimbal 31 to precess so as to rotate thedisc 41 counter-clockwise to the position shown in Fig. 6, therebybringing the probe 49 into registry with the notch 47.

Reverting now for a moment, let it be assumed that the disc 41 was insuch position that the 'lower'segment 42 was in registry with the probe49. In this event, when the roller 51 engages the segment 42, theactuating member 58 will have been moved down to such a position thatthe switch probe 93 has been moved outwardly by engagement with the camsegment or section 59b. In this event, the reversing switch 94 will havebeen operbals are free.

ated to its lower position in Fig. 14 and the motor 72 will have beenreversed, thus the actuati'ng'member 58 will now be caused to rotateinthe opposite direction as before described, the roller 82 will. rideon the torque ring 83 until it snaps into the notch 8,5. Now, however,the torque applied to the outer gimbal 29. will be 'in'the oppositedirection and the inner gimbal 31 will precess so as to cause the disc41 to rotate to the position shown in Fig. 6

Thus it will be seen that no matter how the inner gimbal is positionedwith respect to the outer' gimbal, the sensing means willoperate so asto cause the'inner gimbal. to be moved to its caged position withrespect to tbe outer gimbal so that the probe 49 may move into the notch 47 and thus latch the innergimbal to the outer gimbal in cagedposition.

When the roller 51 registers with the notch 47 the probe 49 will movedownward under the compression force of the spring 87. Said; movementwill be stopped by engagement of the upper roller 96 on the probe49 withthe track 97. At this moment, the roller 51, will be in position 510,shown in Fig.' 10, and the probe 93 will be hearing against either thesegment 590 or the segment 5900 on the hub 59. Thus the inner gimbal31'will be fixed or latched in its caged position to the outergimbal'29, although this latching will be rather loose as shown in Fig.10'. -Whereas the outer gimbal 29 was virtually immovable as long as theinner gimbal was allowed to precess, once the inner gimbal is latched tothe outer gimbal, the outer gimbal may be readily rotated by virtue ofthe torque applied to it through the torque pin 81.

The direction of the torque applied to the outer gimbal'29, will bedependent upon the reversing switch 94 which will have been actuatedtosuch a position by'either the cam 590 or the cam 59cc that a minimumlengthof travel is required to bring the roller 96 into registry withthe notch 104 in the track 97. Hence, the motor 72 now drives the hub 69and the outer gimbal 29so as to rotate the outer gimbal until the roller96 drops into the notch 104 on the track 97.

When this occurs both rollers 96 and 51 will firmly seat in theirrespective notches, thus caging the outer gimbal 29' to the frame 21 andalso removing the'tolerance in the caging of the inner gimbal to theouter gimbal as the roller 51 drops into the tapered portion 48.

position by virtue of the continued engagement of the toe 86in thegroove 92.

Uncaging is effected simply by opening the switch 137. Such openingde-euergiz'es the solenoid 107 allowing spring 109 to retract toe 86thus allowing the driving ring 73 tobe driven quickly and linearlyupward in the cavity 74 of the hub 59"by spring 87. This operati'on isaccompanied by a rapid lifting of the entire actuating memberSS byvirtue of the spring 88. This rapid and linear lifting of the actuatingmember 58 releases the outer gimbal 29 and simultaneously releases theinner gimbal 31. The caging mechanism parts thus quickly resume theirde-energized positions in which both gimly and without any disturbanceor kicks which might impart an undesired torque to either gimbal.

In this releasing operation the caged switch is first moved to its upperposition in Fig. 14 and immediately This release it will be noted occursrapid-' 15 thereafter the uncaged switch is closed as the annular plate61 engages the pin 118 (Fig. to close the switch 116. Thus the lamp 144will burn dimly in series with lamp 143 for a moment (during uncagingoperation) and then go dark as lamp 143 attains full brillianceindicating that the gyroscope is in uncaged position.

It will be noted that should the uncaging be impeded, the two lamps willburn dimly thus indicating to the operator a malfunctioning of theapparatus. Thus no phase of the operation is indicated by a dark lamp,which would be ambiguous with a burned-out lamp.

From the above description, it is noted that the caging operation iseffected by a rotary motion of the driving ring 73. This rotary motionby virtue of the thread 76 may be made against the opposition of strongsprings 88 and 87, without requiring much operating power; at the sametime the springs 87 and 88 may be made strong enough to overcome anyhigh acceleration in the air vehicle. At the same time the uncagingoperation is achieved by a linear motion of the driving ring 73 therebybeing effected rapidly and without undesirable disturbance of thegimbals.

It will be further noted that the system is a fail-safe system in thatif the power should be cut off, either during the operation of themechanism or when it is being maintained in caged position, it willimmediately revert to uncaged position which is the safer of the twopossible attitudes of the system.

While the modification shown in Figs. and 16 is more suited for low Gwork than for high G work, it does have the advantage of simplicity inthat not as many moving parts are required and the transfer switch maybe eliminated. The transfer switch is required in the first embodimentbecause of the danger that the reversing switch 94 might be operatedbefore the thread engaging toe 86 has snapped into the upper groove 92,in which event the screw down operation would be reversed prior tocompletion.

While the instant invention has been shown and described herein in whatis conceived to be the most practical and preferred embodiment, it isrecognized that departures may be made therefrom within the scope of theinvention which is therefore not to be limited to the details disclosedherein but is to be accorded the full scope of the claims.

What is claimed is:

1. Mounting for a gyroscope spin motor shaft comprising: a gimbal framehaving a pair of spaced, substantially parallel arms, a spin motor shafthaving its ends fitted closely between said arms within said frame, eachend of said shaft being secured to the adjacent frame arm by meanscomprising aligned bores in shaft and arm of substantially equaldiameter, at least one of said frame arms having a lateral grooveextending from one side thereof to the bore in said frame arm fortemporarily receiving and providing passage for electric wiringextending generally axially from said shaft, during positioning of saidshaft within said frame, said shaft having a threaded bore slightlysmaller in diameter than the common bore in said shaft and arm andforming a coaxially inward continuation of said bore, and a pin joiningsaid shaft to said arm having its inner end threaded and engaged in thethreaded bore in the shaft and having an unthreaded smooth portionclosely engaged in said 'alignedbores, said pin having a head bearingagainst said frame for drawing said shaft into close butting engagementwith and Within said frame.

2. Rigid, precise-mounting for a member comprising a pair of spacedarms, a member fitted between and closely within said arms, aligned,smooth bores in each arm'and the adjacent portion of said member, atleast one of said arms having a lateral groove extending from one sidethereof to the bore in said arm for temporarily receiving and providingpassage for electric wiring extending from said member, duringpositioning of said member within said arms, each bore in said memberbeing extended by a coaxial threaded bore slightly smaller than saidsmooth bore, pins joining said member to said arms and having inner endsthreaded into said threaded bores and having smooth unthreaded portionsclosely engaged in said smooth bores, and heads on said pins bearingagainst said arms for holding said member firmly and precisely within"and between said arms.

3. Means for mounting an elongate member between and within the arms ofa bifurcated member, comprising: a bifurcated member having two spacedgenerally parallel arms, an elongate member having its ends fittedclosely between and within said arms, each end of said member beingsecured to the adjacent arm by means comprising: aligned bores in memberand arm of substantially equal diameter, at least one of said armshaving a lateral groove extending from one side thereof to the bore insaid arm for temporarily receiving and providing passage for electricwiring extending from one end of said member, during positioning of saidmember within said arms, said member having a threaded bore slightlysmaller in diameter than the common bore in said member and arm andforming a coaxially inward continuation of said member bore, and a pinjoining said member to said arm, having an inner end threaded andengaged in the threaded bore in the member and having an unthreadedsmooth portion closely engaged in said aligned bore, said pin having ahead bearing against said arm for drawing said member into close buttingengagement with said arm.

4. Rigid, precise mounting means for a member comprising: a pair ofspaced arms, a member fitted between and closely within said arms,aligned bores in each arm and the adjacent portion of said member, atleast one of said arms having a lateral groove extending from one sidethereof to the bore in said arm for temporarily receiving and providingpassage for electric wiring extending from said member duringpositioning of said member within said arms, pin means joining saidmember to said arms having portions engaged in said bores, and means forholding said pin means in position in their respective bores.

5. Rigid, precise mounting means for a body comprising: a pair of spacedarms, one of said arms constituting a firstmember, a body engagedbetween and closely within said arms, said body constituting a secondmember, a bore in said one arm aligned with said body, a wire projectingfrom said body through said bore, a groove in one of said members formedon one of the engaging faces of said members and extending radiallyoutward from said bore to temporarily receive and provide passage forsaid wire during positioning of said body within said arms, pin meansfor joining said members together and having a portion engaged in saidbore, and means for holding said pin means in position in said bore.

References Cited in the file of this patent UNITED STATES PATENTS1,067,808 Fuchs July 22, 1913 1,954,998 Hofim'ann Apr. 17, 19342,324,373 Dusevoir July 13, 1943 2,331,541 Dusevoir Oct. 12, 19432,608,598 Hawkins et al. Aug. 26, 1952

